1. Field of the Invention
The present invention relates to vehicles having interface modules in a control network with distributed I/O interfacing. In a particularly preferred aspect, the invention relates to a vehicle having interface modules in a control network with distributed I/O interfacing, wherein the interface modules are configured to maintain one or more outputs in the event of one or more failures in the control network.
2. Description of Related Art
Fire fighting vehicles, aircraft rescue and fire fighting (“ARFF”) vehicles, military vehicles, and other heavy duty vehicles carry a significant amount of electrical and electromechanical equipment that is useful in performing tasks associated with the vehicle. It is common for fire trucks to have well in excess of one hundred individual electrical output devices, especially if the fire truck includes an aerial system.
It has become accepted practice to provide heavy duty vehicles with an additional level of control through the use of interlock systems and/or other control electronics. Interlock systems are used to ensure that one or more predetermined I/O status conditions are met before power is supplied (or continues to be supplied) to a particular output device. For example, many modern fire trucks have control logic to control the vehicles' water pumping function. In order for the pumping function controls logic to allow the vehicle to continue and/or begin pumping water, for example, the interlock system might require that (1) the ignition be turned on, (2) the parking brake be activated, and (3) the transmission be in fourth gear lock-up. The purpose of such an interlock, for example, is to prevent the fire truck from accidentally pumping water while travelling down the road.
Control systems have been developed that allow vehicle output devices to be connected to interface modules which control the output devices and which connect to other system I/O devices via a communication network. Such control systems reduce vehicle wiring and may be used to implement interlocks and other control logic.
However, failure conditions can occur in the any one of a number of components in the control network or associated components. Such failure conditions can include a power glitch that temporarily interrupts power, a component failure, a central controller failure, or any other type of failure. Heavy duty vehicles are often utilized in adverse conditions where the chance of a failure is higher despite efforts to prevent them. Such a failure condition may result in the loss or temporary interruption of data being transmitted to and/or from an electronic module or a central controller.
A failure condition can interfere with control of a function being controlled by an output device. For example, an output device can be controlled to provide a lighting function based on upon receipt of a data transmission. When an interruption of data transmission occurs, the output device can be placed in a default state, usually off, until the failure condition is resolved.
However, some functions should not necessarily be disabled in the event of a failure condition. For a fire truck, the water pumping function is important for extinguishing fire and should not be disabled under normal circumstances. Accordingly, this function can be designated as a mission critical function.
What is needed is a control system that is configured to provide enhanced robustness against failure conditions in connection with mission critical functions. What is further need is such modules that can be configured to operate under a plurality of differing failure conditions based on the nature of the failure condition.